In recent years proliferative skin diseases have been treated successfully to alleviate such diseases by certain types of therapeutically active compounds administered in association with a pharmaceutical carrier. The expression "proliferative skin diseases" has developed an art-accepted meaning, namely, benign and malignant inflammatory and/or proliferative skin diseases which are characterized by accelerated cell division in the epithelium of the skin (epidermis) and the support tissues of the skin (dermis) or appendages thereto, and which are associated with incomplete tissue differentiation. Such diseases include: psoriasis, atopic dermatitis, non-specific dermatitis, primary irritant contact dermatitis, allergic contact dermatitis, basal and squamous cell carcinomas of the skin, lamellar ichthyosis, epidermolytic hyper-keratosis, premalignant sun-induced keratosis, non-malignant keratosis, acne, and seborrheic dermatitis in humans and atopic dermatitis and mange in domesticated animals.
Active compounds capable of alleviating a skin proliferative disease have typically been applied as a composition including a pharmaceutical carrier either topically, orally, injection, intra-dermally, intra- or peri-lesionally or subcutaneously. Certain of these therapeutically active compositions are most effective when applied topically while others work better when applied systemically, either orally or by injection. On the other hand, certain of the compounds penetrate the skin only with great difficulty and are difficult to use effectively when applied topically; other of such compositions which are capable of alleviating an inflammatory and/or proliferative skin disease when administered systemically are medically unacceptable because of the adverse pharmacological reactions which result from the administration of a dosage sufficiently large to alleviate such disease. It has, therefore, become recognized that there is a substantial problem of providing the necessary quantity of the therapeutically active material at the site of the lesion, or other representation of such inflammatory and/or proliferative skin diseases, with many of the compositions which are therapeutically capable of alleviating such disease and concurrently avoiding adverse systemic side reactions. This invention provides a solution to the problem of continuously providing at the desired site the needed quantity of at least one therapeutically active composition while simultaneously overcoming the previously encountered problems with certain compositions of skin penetration and/or medically unacceptable toxicity to the system when systemically administered.